Carrier-mediated nonlocal ferromagnetic coupling between local magnetic polarons in Fe-doped In2O3 and Co-doped ZnO

The combined roles of oxygen vacancy and electron doping in mediating local and nonlocal magnetic ordering of Fe doped in In2O3 and Co doped in ZnO have been investigated within first-principles density functional theory. We first show theoretically that two magnetic dopants can be stabilized energetically around an oxygen vacancy, and are ferromagnetically coupled to form a local magnetic polaron. Furthermore, electron doping plays the elegant dual role of further enhancing the ferromagnetic stability of a local polaron, and more crucially, mediating the nonlocal magnetic coupling between two polarons. Finally, we provide experimental evidence supporting these strong predictions.